Error- and loss-tolerant bundle fragment authentication for space DTNs

To ensure the authenticity and integrity of bundles, the in-transit PDUs of bundle protocol （BP） in space delay/disruption-tolerant networks （DTNs）, the bundle security protocol specification （IRTF RFC6257） suggested using a digital signature directly over each bundle. However, when bundle fragment services are needed, this mechanism suffers from heavy computational costs, bandwidth overheads and energy consumption. In this paper, we address the fragment authentication issue for BP by exploiting the combination of RS error correction and erasure codes with the help of batch transmission characteristic of DTNs. The RS error correction and erasure codes are adopted to allow the receivers to locate the false/injected fragments and reconstruct the only one signature shared by all fragments of a bundle, even if some other fragments are lost or routed to a different path. Getting only partial authentic fragments, a DTN node is able to detect and filter the false/injected fragments, and authenticate the origin of a bundle as well. Such an approach tolerates high delays, unexpected link disruption and the BP nature of routing fragments of the same bundle possibly via different paths. The performance analysis demonstrates that both of our schemes, which follow our generic idea based on RS codes, significantly reduce bandwidth overheads and computational costs as compared to the prior works.     

Environmental Monitoring in Museums Based on Wireless Sensor Network via Cell Phone

Conservation of artworks in museums is a crucial issue to prevent their degradation. Thus, it is fundamental to continuously monitor the environment where artifacts are located. The WISE-MUSE project proposes the use of WSNs （wireless sensor networks） to carry out monitoring and automatically control of museums＇ environment and structural health. The deployment of a WSN can help to implement these measurements continuously, in a real-time basis, and in a much easier and cheaper way than when using traditional measuring equipment and procedures. Nevertheless, continuous monitoring implies providing immediate information of any abnormal value detected in the museums＇ environment. Thus, this contribution arises： the development of a new mobile application that allows users to continuously monitor the environment, but specially helps them to be more aware of any undesirable changes that may occur.     

The Global Crisis and Academic Communication： The Challenge of Social Networks in Research

The global economic crisis is seriously affecting academic research. The situation is provoking some big changes and an urgent need to seek alternatives to traditional models. It is as if the academic community was reinventing itself; and this reinvention is happening online. Faced with a lack of funding, researchers have determined to help each other develop their projects and they are doing so on social knowledge networks that they have created for this mission. The purpose of this paper is to analyze different social networks designed for academic online research. To this end, we have made a selection of these networks and established the parameters for their study in order to determine what they consist of, what tools they make use of, what advantages they offer and the degree to which they are bringing about a revolution in how research is carried out. This analysis is conducted from both a qualitative and a quantitative perspective, allowing us to identify the percentage of these networks that approach what would be the ideal social knowledge network. As we will be able to confirm, the closer they are to this ideal, the more effective they will be and the better future they will have, which will also depend on the commitment of users to participation and the quality of their contributions.     

Towards Effective Integrated Access Control Lists in Internet Networks

ACLs （access control lists） represent a traditional way in filtering packets in routers. In modern complex enterprise networks that provide a vast array of services, there is an ever increasing need for verifying the integrity of ACLs to detect any potential security holes and improve the network performance. This paper concerns the integrity of routers＇ ACLs in large enterprise networks. We first investigate the integrity of the ACLs of two touters by describing a bottom-up approach for detecting redundancies in ACLs of two routers. We then extend our study to multiple touters and provide a heuristic algorithm for detecting redundant ACLs in multiple touters. We validate the practicality of ouralgorithm through real-life and synthetic router ACL groups of large networks. Performance results show that our heuristic algorithm do not only improve the performance by reducing the number of comparisons overhead, but also helps in discovering potential security holes that can not be discovered by considering the ACLs of each router individually.     

Performance Evaluation of a Markovian Policy for Macro/Femto User Allocation Considering Aspects of QoS,QoE and Energy Efficiency

The advancement of wireless networks offers mobile users a diversity connectivity options, but the choice of the best connection should consider classics QoS aspects and, with increasing multimedia applications, should also consider QoE metrics. Another important parameter to choose the best connection is the energy efficiency by reducing the battery consumption of the devices and reducing CO2 emissions （green network）. This paper validates a Markovian policy for distribution of user load balancing in femtocell/macrocell networks considering QoS/QoE and energy consumption providing quality for multimedia applications. The results obtained by simulation proved the benefits.     

Performance analysis of three multi-radio access control policies in heterogeneous wireless networks

Access control policy in wireless networks has a significant impact on QoS satisfaction and resource utilization efficiency. The design of access control policy in heterogeneous wireless networks （HWNs） becomes more challenging especially for the heterogeneous multiple access protocols of each radio network. In this paper, a Markov model is proposed to analyze the performance of three access control policies for HWNs. The first policy is the optimal radio access technology （O-RAT） selection, where the incoming traffic always tries to access one network with the maximum service rate before admission. The second policy intends to allocate the same data to all networks. And the traffic will leave the system if it is accomplished first by one of these networks, which is formulated as the aggregated multi-radio access （A-MRA） technology. The third policy is named the parallel multi-radio access （P-MRA） transmission, in which the incoming traffic is split into different networks. The traffic is served with the sum of the service rates provided by overall networks. Numerical and simulate results show the effectiveness of our analytical framework and the performance gain of the three access control policies. As illustrated with some representative results, the P-MRA policy shows superior performance gain to the other two policies independent on the specific parameters of the different multiple access protocols due to the multiplexing gain.     

Behavior of Pendulums on a Regular Polygon

Stochastic and deterministic versions of a discrete dynamical network system are investigated. This network consists of a sequence of contours NSWE with nodes, which are common points atN, W, S and E. There are four cells and a particle on each contour At each time instance, the particle occupies a cell, and attempts to occupy the next cell in the same direction. Particles of neighboring contours move in accordance with some rules. Both deterministic and stochastic rules are considered. The behavior of the model with the first rule is stochastic only at the beginning, and after a time interval the system becomes to pure deterministic. The system with the second rule comes to a steady state, which depends on the initial state. The average velocity of particles and other characteristics of the system are studied.     

A top-down positioning scheme for underwater wireless sensor networks

In order to increase the localization coverage while keeping the localization error small in a unique network architecture in which there are not evenly distributed anchor nodes with great ability of communication or additional infrastructure,a Top-down Positioning Scheme(TPS)for underwater acoustic sensor networks is proposed.By defining node’s confidence reasonably,TPS insures the quality of the new reference nodes.TPS also refines the nodes which have just been positioned via the gradient method and helps non-localized nodes search for more reference nodes via the new scheme for 3D Euclidean distance estimation.By comparing the new scheme for 3D Euclidean distance estimation with the existing scheme,the new scheme is shown to have greater ability to estimate two-hop Euclidean distance in 3D space.Simulation results show that TPS which integrates node’s confidence defined reasonably,the gradient method,and the new scheme for 3D Euclidean distance estimation can increase the localization coverage ratio,while keeping the localization error small.     

分层抽样的无标度复杂网络可靠性度量算法

针对大型无标度复杂网络的幂律分布特性,提出了一种基于分层抽样技术的算法SSBA,通过分析样本网络推导出大型无标度复杂网络的可靠性度量参数,并给出这些参数的Bootstrap置信区间。大量的实验表明,SSBA算法能有效估算出大型无标度复杂网络的可靠性度量参数。     

复杂网络聚类算法在生物网络中的应用

复杂网络在现实世界中普遍存在,具有小世界性和无标度性等统计特性,网络簇结构是复杂网络重要的拓扑属性之一。在复杂生物网络中使用聚类算法揭示生物网络中的簇结构对分析生物网络的拓扑结构、预测其功能都具有重要意义。对复杂网络聚类方法在蛋白质-蛋白质相互作用网络和新陈代谢网络中的应用及其进展情况进行了综述,分析了几种聚类算法的评价函数和适用条件,并对生物网络聚类算法研究所面临的主要问题进行了讨论。     

改进的BA 网络演化模型的研究及应用

利用主方程和连续域理论分析了BA无标度网络的度分布以及初始吸引因子对网络节点度分布的演化过程。对BA模型进行了改进和推广,提出了随机吸引因子网络演化模型。此网络演化模型通过理论分析和数值模拟验证是吻合的,该模型是无标度网络演化模型。实验结果表明,改进的模型能够很好地反映现实系统中的一些重要性质,具有实际应用价值。     

一种具有核心-边缘结构的无标度网络演化模型

核心-边缘结构是复杂网络中一种重要且常见的簇团结构,相关研究一直较少。为了研究复杂网络核心-边缘结构的相关特性,分析了随机块模型的结构,并在此基础上提出了一种具有无标度特性的核心-边缘结构网络演化模型。通过理论和数值分析,验证了所生成的网络具有较好的无标度特性和核心-边缘结构,且其结构的紧密程度可调,为进一步研究复杂网络核心-边缘结构的相关特性提供了基础。     

无尺度网络中集散节点的抗脆弱性策略

回顾了无尺度网络的发现历程,论述了复杂网络的无尺度特性,并在此基础上提出了集散节点的抗脆弱性策略。提出了对集散节点加以控制后形成的层次和由虚拟节点组成的超立方体。与原集散节点相比较,层次结构具有较高的灵活性和容错性,超立方体结构具有高度自治性与故障重构性。仿真实验表明两者都具有较强的鲁棒性、稳健性。     

加权无标度网络病毒传播和局部免疫策略研究

为了进一步描述现实生活中复杂网络的病毒传播问题,改进加权无标度网络模型的传统构造方法,考虑流量带宽和个体抵抗力两个重要因子,利用平均场理论模拟仿真病毒传播过程,对实验数据进行分析,验证该模型的有效性.现实生活中往往只能了解复杂网络的局部拓扑信息,传统病毒免疫策略大多基于全局拓扑信息,在仅了解局部信息的前提下,提出加权无标度网络中基于局部最优的病毒免疫策略,通过动态模拟病毒传播的免疫仿真实验,与随机免疫策略和目标免疫策略对病毒传播影响进行比较,验证局部最优免疫策略的有效性.     

无尺度网络分析与研究

讲述了无尺度网络的发现及其特性,介绍了无尺度网络对于科学研究的意义,并指出了其面临的挑战。     

Patient-Oriented Web Telemedicine System for Health Monitoring

WBAN （wireless body area network） helps in monitoring vital signs of a patient and can monitor patient＇s history in routine life activities to provide them accurate diagnosis. Doctors can check the complete details of patients from remote location and can recommend a suitable medication. The main purpose of this technology is to reduce the load at hospitals and provide efficient healthcare facility remotely. To monitor the patients in their natural environments is not practical when devices or sensors are connected through a wire that is why we use WBAN to carrying out daily activities through unobtrusive and contented way. In these networks, various sensors are attached on clothing or on the body or even implanted under the skin. The wireless nature of the network and the wide variety of sensors offer numerous new, practical and innovative applications to improve health care and the quality of life. Using a WBAN, the patient experiences a greater physical mobility and is no longer compelled to stay in the hospital. This technology can provide very cheaper, easier and quick respondent history of patient. This paper discusses the architecture of WBAN, and its position between different technologies. The paper also introduces the web portal telemedicine solution, and the implementation oftelemedicine monitoring system using WBAN.     

复杂客户网络拓扑性质研究

运用复杂网络的理论来研究客户网络的建立和发展复杂客户网络,通过对复杂客户网的小世界和无标度性质的分析来证实客户网络是一个复杂网络。并具备点分布、平均路径长度、聚集数等拓扑性质,研究结论对于企业赢得客户和保持客户规模具有指导意义。     

基于复杂网络的操作系统内核演化与稳定性研究

出了基于复杂网络研究操作系统内核模块演化的方法.通过研究223个Linux版本(从1.1.0到2.4.35)内核模块函数调用图的度分布和平均路径长度,发现函数调用图具有无标度和小世界特征.根据复杂网络中平均路径长度与网络节点的关系,提出了通过平均路径长度斜率发现演化过程中的异常点,从而发现内核模块结构重大变化的方法.提...     

灰色信息下复杂负载网络的鲁棒性研究

针对复杂负载网络遭遇攻击引发的相继故障问题,考虑攻击信息的不完全准确性,建立了一个基于灰色信息的相继故障模型。灰色信息的准确度可以通过参数调节控制,随机攻击和蓄意攻击是该模型的两个特例。探讨了灰色信息下,无标度网络和随机网络遭遇边攻击而引发的节点过载故障的级联现象,对比了灰色信息对两类网络鲁棒性的影响。仿真结果表明,信息准确度的降低能明显增强无标度网络的鲁棒性,但对随机网络的影响并不明显。此外,信息准确度对网络鲁棒性的影响存在临界现象。这些结论为相继故障的防御、网络结构的设计以及现实网络的有效保护提供了理论依据。     

无线传感器网络簇级拓扑演化模型研究

复杂网络理论研究表明,复杂系统的容错能力不仅仅存在于具有冗余组件的系统之中;而且也同样存在于具有无标度(scale-free)特征的网络之中;文章借助于复杂网络理论和偏好依附机制提出一种无线传感器网络簇级拓扑演化模型;拓扑动态分析表明,该模型能够很好地体现无线传感器簇间的拓扑生长过程,由该模型演化成的无线网络拓扑具有无标度网络的性质,所以该拓扑模型具有很强的容错性。